Paint is an expensive commodity. So when house painting, you need to choose wisely when it comes to paint colours and colour selection. There are many ranges of colours across the full spectrum, in all the paint suppliers brochures.
Some paints are more expensive than others, and for good reason; the quality of the paint, covering capacity and consistency of colour in the batches, to name a few. However, there are very good standard brands where one can successfully mix one brands colour into another brands base. This works very well with lighter colours regarding the accuracy of the replicated colour. The darker the colour the less accurate the copied colour will be.
Some brands have a distinctive quality to the finish of the paint which will not be copied even if the colour is correct. But it still means you have the option of choosing across the board when it comes to painting your house the colours you want.